School of Environment, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, People's Republic of China.
Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, Queensland, 4072, Australia.
Environ Sci Pollut Res Int. 2018 May;25(13):12434-12443. doi: 10.1007/s11356-018-1430-7. Epub 2018 Feb 19.
Syntrophic acetogenesis of volatile fatty acids (VFAs) such as propionate and butyrate is considered as the rate-limiting step of anaerobic digestion. Though being extensively researched, the mechanism is not well understood as the main constraint on developing effective solutions to the practical problem. In the present research work, the mediation of methanogenic propionate degradation by exogenous bicarbonate was evaluated, while the mechanism was revealed by microbial community and thermodynamics. It was found that the exogenous bicarbonate not more than 0.10 mol/L acted as a mediative role to enrich syntrophic acetogenic bacteria and decrease the actual Gibbs free energy change (ΔG) of syntrophic acetogenesis reaction, resulted in the increased degradation rate and methane production rate of propionate. The remarkably increased ΔG of methanogenic propionate degradation by the exogenous bicarbonate more than 0.15 mol/L decreased the degradation rate and methane production rate of propionate, though the ΔG of syntrophic acetogenesis reaction was also decreased by the exogenous bicarbonate. This research work provided a control strategy to enhance syntrophic acetogenesis, as well as the methanogenic VFAs degradation.
挥发性脂肪酸（VFAs）如丙酸和丁酸的协同产乙酸作用被认为是厌氧消化的限速步骤。尽管已经进行了广泛的研究，但由于这是开发有效解决实际问题的方法的主要限制因素，因此其机制仍未得到很好的理解。在本研究工作中，评估了外源碳酸氢盐对产甲烷丙酸降解的介导作用，同时通过微生物群落和热力学揭示了其作用机制。结果发现，不超过 0.10 mol/L 的外源碳酸氢盐起到了介导作用，富集了协同产乙酸细菌，并降低了协同产乙酸反应的实际吉布斯自由能变化（ΔG），从而提高了丙酸的降解速率和甲烷生成速率。而当外源碳酸氢盐超过 0.15 mol/L 时，协同产乙酸反应的 ΔG 也降低了，但由于外源碳酸氢盐的存在，丙酸的降解速率和甲烷生成速率明显降低。这项研究工作为增强协同产乙酸作用以及产甲烷 VFAs 降解提供了一种控制策略。
